Delivery system and method of making article

ABSTRACT

A water treatment composition comprised of a metal ion yielding material secured to an adhesive, with the adhesive secured to a structure, so that when the structure is placed in a body of water the concentration of metal ions is maintained at level sufficient to kill bacteria and sufficient to permit release of metal ions over an extended period of time. Also, a method of securing a metal ion yielding material, as well as a method of manufacture of an article, by first adhering the metal ion yielding material to a structure and then forming the structure into an article for placement in a body of water to maintain the desired metal ion concentration therein.

CROSS-REFERENCE TO RELATED APPLICATIONS, IF ANY

[0001] This application claims the benefits under 35 U.S.C. §119(e) ofco-pending provisional application Serial No. 60/177,558, filed Jan. 21,2000. Application Serial No. 60/177,558, is hereby incorporated byreference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] Not applicable.

REFERENCE TO A MICROFICHE APPENDIX, IF ANY

[0003] Not applicable.

FIELD OF THE INVENTION

[0004] This invention relates generally to water treatment mechanismsand, more specifically, to the combination of a metal ion yieldingmaterial supported by a triple acting adhesive that firstly securesitself to the metal ion yielding material, secondly provides acontrolled release of metal ions over a range of water temperatures andthirdly, simultaneously therewith secures the metal ion yieldingmaterial to a structure within the water system The invention alsorelates to a method of manufacture of articles with a metal ion yieldingmaterial thereon including methods of securing the metal ion yieldingmaterial to a processable material that can be formed into a working ornon-working structure that when placed in water to be purified providesa controlled released of metal ions to thereby continually rid the waterof bacteria.

BACKGROUND OF THE INVENTION

[0005] In water treatment systems it is known that small amounts ofmetal ions are effective as a bacteria killing material. Suitable metalions that are use useful in killing bacteria are silver, zinc, copper,and tin. While it is known that such metal ions are effective in killingbacteria in water systems it is necessary to maintain a controlledrelease of the metal ions in order to provide bacteria killing over anextended period of time. In addition, to provide a controlled release ofmetal ions, it is necessary to maintain the concentration of metal ionsin water at sufficient levels to kill bacteria, yet not sufficientlyhigh so as to cause the metal ions to come out of solution. In addition,as the water system temperature can vary it is desirable to maintain acontrolled release of metal ions over a range of water temperatures. Inthe present invention a metal ion yielding material is maintained in acontrolled bacteria killing state by an adhesive that supports the metalion yielding material in a body of water while simultaneously releasingmetal ions to provide for bacteria killing over an extended period oftime and in different water temperatures. That is, the adhesive, whichremains unreactive to the bacteria killing chemicals, supports the metalion yielding material in a condition that allows metal ions to migratetherefrom at a sufficiently slow rate so that the metal ionconcentration in water remains within acceptable levels.

SUMMARY OF THE INVENTION

[0006] Briefly, the present invention comprises a water treatmentcomposition comprised of a metal ion yielding material secured to anadhesive with the adhesive secured to a structure so that when thestructure is placed in a body of water the concentration of aqueousmetal ions is maintained at levels sufficient to kill bacteria and thesecured metal ion yielding material is sufficient to permit release ofmetal ions over an extended period of time. The invention furthercomprises methods of securing a metal ion yielding material, as well asa method of manufacture of an article, by first adhering the metal ionyielding material to a structure and then forming the structure into anarticle that can be placed in a body of water to maintain the propermetal ion concentration therein.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007]FIG. 1 shows a method of applying water purification materials toa web using a spray coating method;

[0008]FIG. 2 shows a method of applying water purification materials toa web using a calendar roll coating method;

[0009]FIG. 3 shows a method of applying water purification materials toa web using a knife-over-web method;

[0010]FIG. 4 shows a method of applying water purification materials tostrips of material using an immersion coating method;

[0011]FIG. 5 shows a slurry coating method of applying waterpurification materials to a web using a die coater;

[0012]FIG. 6 shows a slurry coating method of applying waterpurification materials to a web using a calendar roll coater;

[0013]FIG. 7 shows a transfer coating method of applying waterpurification materials to a semi-finished product; and

[0014]FIG. 8 shows a die coating method of applying water purificationmaterials to a web.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0015] While numerous materials are capable of killing water bornebacteria, not all materials are capable of killing bacteria whileremaining non-toxic to humans. In addition, the bacteria killingmaterials need to be maintained at acceptable levels for an extendedperiod of time in order to provide safe water. It is known that metalions such as zinc ions, copper ions, silver ions, and tin ions aresuitable for killing bacteria. However, the use of metal ions requires adelivery mechanism that can both yield the metal ions and maintain themetal ion aqueous concentration within acceptable levels. In the presentinvention a metal ion yielding material is meant to be understood as oneor more compounds that, in the presence of water, yields the metal ionsfrom the compound(s). In the preferred embodiment the metal ion yieldingmaterial comprises compounds selected from the group consisting of zincsulfate, zinc carbonate, zinc chloride, copper chloride, coppercarbonate, copper sulfate, silver chloride, stannous chloride andstannic chloride. Each of the above compounds is capable of yieldingmetal ions. For example zinc carbonate, zinc chloride and zinc sulfateare all capable of yielding zinc ions when placed in water. Similarly,copper chloride, copper carbonate, and copper sulfate all yield copperions when placed in water. Silver chloride yields silver ions whenplaced in water and stannous chloride and stannic chloride yield tinions. Unfortunately, if the metal ion yielding materials are placeddirectly in water, the concentrations of the metal ions rapidly increaseto reach unacceptable levels. For example, if excessive copper ions arepresent in the water, the copper ions begin to plate out on any fixturesin the pool, thus coating the pool fixtures with an unwanted andunsightly coating of copper. In addition, the surge of metal ions intothe water causes a rapid decrease in the ability to provide long termbacteria control. In still other cases metal ion concentrations can riseto levels that could be considered toxic. The present invention providesa water treatment composition wherein the metal ion yielding materialsare retained in a condition to controllably release metal ions withinacceptable ranges for water treatment. In order to maintain the metalion yielding materials in a condition to controllably release metal ionsinto the water, a triple acting adhesive is used. By triple actingadhesive, it is meant that the adhesive can secures itself to dissimilarmaterials which may be in either solid or particle form. For example,the adhesive should be able to secure itself to a structure andsimultaneously secure itself to the metal ion yielding material to holdthe metal ion yielding material in position. In addition, the tripleacting adhesive needs to maintain its stability over a wide range ofwater temperatures. The adhesive also needs to limit the amount of metalions that can be released into the water.

[0016] In the preferred embodiment it has been found that fourindividual triple acting adhesives permit securing itself to the metalion yielding material and to a separate structure while furthermaintaining a controlled release of metal ions. The suitable tripleacting adhesives are polyurethane, epoxy resin, polyvinyl alcohol, andpolyvinyl acetate. A triple acting adhesive selected from the groupconsisting of polyurethane, epoxy resin, polyvinyl alcohol and polyvinylacetate provides the controlled release of metal ions from the metal ionyielding materials selected from the group consisting of zinc sulfate,zinc carbonate, zinc chloride, copper chloride, copper carbonate, coppersulfate, silver chloride, stannous chloride and stannic chloride. Thepreferred triple acting adhesive is polyvinyl acetate. Polyvinylacetate, which is a non-toxic adhesive, has been found to secure themetal ion yielding material to a structure or to a mineral which isplaced in the water and at the same time provides a controlled releaseof the metal ions. While the mechanism of the controlled release of themetal ions is not fully understood the use of a water insoluble adhesiveto secure the ion yielding material to the structure results in a watertreatment composition that, when placed in water, maintains the aqueousmetal ion concentration at a suitable level for prolonged bacteriakilling. Polyvinyl acetate has been found particularly suitable since itis nonsoluble in water and maintains its integrity over a range of watertemperatures. For example, a pool may have water at temperatures as lowas 70° F. and a hot tub may have water at temperatures as high as 104°F. Polyvinyl acetate is particularly suited for such applications sinceit has been found that the integrity of polyvinyl acetate is maintainedover a wide range of temperatures, while at the same time polyvinylacetate permits a controlled release of metal ions into the water.

[0017] While polyvinyl acetate is the preferred triple acting adhesive,other triple acting adhesives for securing the metal ion yieldingmaterial, such as polyurethane, epoxy resin, and polyvinyl acetate, alsoprovide a stable yield of metal ions over an extended range of watertemperatures.

[0018] With the present invention the metal ion yielding material can besecured to an inactive structure or to an active structure that isplaced directly in the water supply. For example, the metal ion yieldingmaterial can be affixed to an active structure such as a water filter orto reactive materials that are used to maintain the proper pH of thewater supply. A group of suitable materials for maintaining the pH ofthe water and for supporting the metal ion yielding materials aremagnesium carbonate, magnesium silicate, calcium silicate, calciumoxide, silicon dioxide, and calcium carbonate (limestone) or mixturesthereof. Thus, an active structure selected from the group consisting ofmagnesium carbonate, magnesium silicate, calcium silicate, calciumoxide, silicon dioxide and calcium carbonate or mixtures thereof,provide an active structure that can support the metal ion yieldingmaterial thereon.

[0019] The following example illustrates how the metal ion yieldingmaterial of silver chloride coating was affixed to an active structureof limestone by use of polyvinyl acetate.

EXAMPLE 1

[0020] A batch of water treatment composition was prepared using 20pounds of limestone particles as a structure for carrying the watertreatment material and using a spray coating method wherein the tripleacting adhesive polyvinyl acetate was mixed with the water treatmentmaterial before application to the structure. In order to obtain silverchloride a mixture of 200 grams of silver nitrate was mixed with 74grams of sodium chloride in a mixture of 403 grams of water and 681grams of latex polyvinyl acetate. The mixture containing the silverchloride was sprayed on the limestone which was tumbled in a containerfor ten minutes to distribute the adhesive and the silver chloride overthe limestone. The coated limestone was allowed to dry until it wasnon-tacky to the touch.

[0021] The water treatment composition was placed in a test body ofwater and the total silver ion concentration was measured and rangedfrom 30 to 40 parts per billion with the silver ion concentration beingmaintained at less than 100 parts per billion.

[0022] A test was conducted to measure the dissolution rate of silverfrom the silver chloride coated minerals produce in example 1. The testunit included a four liter glass reservoir, a peristaltic pump and a 6″by 1.5″ cartridge containing the minerals made in accordance with themethod described in example 1. The cartridge containing the minerals wasplaced in the outlet stream of a reservoir with the outlet of thecartridge returning the water to the top of the reservoir. Four litersof city tap water at 75° F. was added to the reservoir and pumpedthrough the system at a flow rate of 20 milliliters per minute. Watersamples were taken from the bottom of the reservoir at the outlet streamof the reservoir at time intervals of 0, 1, 4, 8, 24, 72 and 120 hours.The water samples were analyzed by graphite furnace atomic absorptionspectroscopy for determination of the amount of silver present in theform of colloidal silver and silver ions. The results are as follows:Time (hours) Silver (ppb) 0 1.0 1 4.9 4 18 8 26 24 39 72 39 120 43

EXAMPLE 2

[0023] A batch of water purification composition was made in accordancewith Example 1 except an equal amount of polyurethane was used as thebinder instead of polyvinyl acetate. The test to determine the amount ofsilver present was repeated. The results are as follows: Time (hours)Silver (ppb) 0 1.0 1 1.0 4 23 8 26 24 33 72 37 120 33

[0024] In both examples the measured concentration of silver (includingcolloidal silver and silver ions) was sufficient to kill bacteria yetnot sufficiently high so as to introduce problems because of thepresence of high levels of metal ions. When the metal ion yieldingmaterial yields silver ions, it is desirable to maintain the silverconcentration between 10 and 100 ppb (parts per billion). As can be seenfrom example 1 and 2, within a matter of 4 hours the concentration ofsilver in the reservoir was within the acceptable range. If the metalion yielding material yields zinc or tin ions, the acceptable aqueousconcentration for metal ions generally range from 100 to 2000 parts perbillion (ppb). If the metal ion yielding material yields copper ions,the acceptable copper ion concentration in the water ranges from 800 to1000 parts per billion (ppb)

[0025]FIG. 1 shows a method of applying water purification materials toa web using a spray coating method. In the spray coating method multiplespray heads can be used to apply the adhesive onto a web moving througha chamber. The purpose of the chamber is to prevent contamination of thework area due to over spraying. After the adhesive is applied to theweb, a hopper drops particles of the metal ion yielding material ontothe adhesive. The coated web is then allowed to dry and rewound for usein manufacture of an article for placing in a water system for thepurposes of purifying the water therein.

[0026]FIG. 2 shows a method of applying water purification materials toa web using a calendar roll coating method. In the method using acalendar roll coat two roll coaters are used to roll an adhesive onto amoving web. The rolls are driven and maintained in a squeezing conditionon the web in order to control the thickness of the adhesive applied tothe web. The lower roller is partially submerged in a trough thatcontains a liquid adhesive. As the lower roller rotates it transfers theadhesive onto the moving web. The metal ion yielding particles areapplied to the moving web from a hopper. The entire web can be coatedwith the adhesive, or separate bands can be coated with the metal ionyielding material.

[0027]FIG. 3 shows a method of applying water purification materials toa web using a knife-over-web method. In this knife-over-web method twosteel knives and an adhesive feed assembly are utilized to applyadhesive onto a moving web. Excessive adhesive flows over the web edgesand is recirculated. The web covered with adhesive flows under the knifeto limit the thickness of the adhesive coating on the web. The metal ionyielding particles are applied to the moving web from a hopper.

[0028]FIG. 4 shows a method of applying water purification materials tostrips of material using an immersion coating method. In the immersioncoating method the adhesive is applied to the strips and the metal ionyielding particles are drop coated to the moving article from a hopper.The strips are then adhered to the outside of another structure such asa filter cartridge.

[0029]FIG. 5 shows a slurry coating method of applying waterpurification materials to a web using a die coater. In the slurrycoating method a pressurized chamber or die is utilized to apply amixture of adhesive and metal ion yielding metal onto a moving web. Inthis method the adhesive and metal ion yielding materials aresimultaneously applied to the moving web.

[0030]FIG. 6 shows another slurry coating method of applying waterpurification materials to a web using a calendar roll coater. In thisslurry coating method the adhesive and the metal ion yielding materialare placed in a trough and a roller extends partially into the trough toroll the mixture directly onto a moving web.

[0031]FIG. 7 shows a transfer coating method of applying waterpurification materials to a semi-finished product. In this transfercoating method a preassembled article such as filter contains a transferroll to transfer a layer of adhesive onto the article. A plurality oftransfer rollers can be used to limit the amount of adhesive applied tothe article. The metal ion yielding material is then dropped onto theadhesive. In the method shown one can apply multiple metal ion yieldingmaterials to the article. That is, one strip could contain a first metalion yielding material and the other could contain a different metal inyielding material.

[0032]FIG. 8 shows a die coating method of applying water purificationmaterials to a web. In this die coating method the die coating isapplied to a continuous web, and the metal ion yielding material is dropcoated on the web.

[0033] In the methods of the present invention the water treatmentmaterial is applied to the structure by either applying the adhesive tothe structure and then applying the metal ion yielding material to thestructure or mixing the adhesive with the metal ion yielding materialand then simultaneously applying the mixture of adhesive and metal ionyielding material to the structure.

We claim:
 1. A water treatment composition for maintaining a metal ionaqueous concentration at a bacteria controlling level comprising: ametal ion yielding material selected from the group consisting of zincsulfate, zinc carbonate, zinc chloride, copper chloride, coppercarbonate, copper sulfate, silver chloride, stannous chloride andstannic chloride; a structure; and a triple acting adhesive, said tripleacting adhesive secured to at least one of said metal ion yieldingmaterials, said triple acting adhesive further secured to said structureso that when said structure is placed in a body of water the adhesivesupports said metal ion yielding material in a condition whereby theadhesive remains secured to the structure and to the metal ion yieldingmaterial, with metal ions maintained in water at a concentrationsufficient to kill bacteria therein.
 2. The water treatment compositionof claim 1 wherein the structure is active and comprises particles ofmaterial.
 3. The water treatment composition of claim 1 wherein thestructure is an active structure selected from the group consisting ofmagnesium carbonate, magnesium silicate, calcium silicate, calciumoxide, silicon dioxide and calcium carbonate (limestone) or mixturesthereof.
 4. The water treatment composition of claim 1 wherein thestructure is a strip of material with said strip of material secured toa filter cartridge.
 5. The water treatment composition of claim 1wherein the triple acting adhesive is selected from the group consistingof polyurethane, epoxy resin, polyvinyl alcohol, and polyvinyl acetate.6. The water treatment composition of claim 1 wherein the triple actingadhesive is polyvinyl alcohol.
 7. The water treatment composition ofclaim 1 wherein the metal ion yielding material is silver chloride andthe triple acting adhesive is polyvinyl acetate with an aqueous silverion concentration maintained between 10 and 100 parts per billion (ppb).8. A method of applying a water treatment composition to an articlecomprising the steps of: a) applying an adhesive to a web of material;b) applying a metal ion yielding material in particle form to theadhesive on the web; c) allowing the adhesive to dry; and d) forming theparticle containing web into an article for use in water purification.9. The method of claim 8 wherein the particle containing web is formedinto a filter.
 10. A method of making an article for insitu watertreatment comprising the steps of: selecting a water treatment materialfrom the group consisting of zinc sulfate, zinc carbonate, zincchloride, copper chloride, copper carbonate, copper sulfate, silverchloride, stannous chloride and stannic chloride; selecting an adhesivefrom the group consisting of polyurethane, epoxy resin, polyvinylacetate and polyvinyl alcohol; selecting a water insoluble solidstructure; applying the adhesive to the water insoluble solid structureto form at least a partial coating thereon; applying the water treatmentmaterial to the adhesive on said solid structure; allowing the adhesiveto set to thereby secure the water treatment material to the solidstructure; and forming the structure into an article for placement intoa body of water to thereby enable the structure to adhesively supportthe water treatment material thereon in a condition that maintains awater concentration of metal ions less than 1000 parts per billion(ppb).
 11. The method of claim 10 wherein the selected adhesive andselected water treatment material are combined in a slurry andsimultaneously coated onto the structure using a die coater.
 12. Themethod of claim 10 wherein the selected adhesive is sprayed on the solidstructure and the selected water treatment material is applied to theadhesive on the structure.
 13. The method of claim 10 wherein theselected adhesive is roll coated onto the structure and the selectedwater treatment material is applied to the roll coated adhesive on thestructure.
 14. The method of claim 10 wherein the selected adhesive isdie coated onto the structure and the selected water treatment materialis applied to the die coated adhesive on the structure.
 15. The methodof claim 10 wherein the solid structure is immersed into the selectedadhesive and the selected water treatment material is applied to theadhesive after the structure is removed from the adhesive.
 16. Themethod of claim 10 wherein the selected adhesive applied to the solidstructure is limited by a knife and the selected water treatmentmaterial is applied to the adhesive on the structure.
 17. The method ofclaim 10 wherein the selected adhesive is roll coated onto the structureand the selected water treatment material is roll coated on the adhesiveon the structure.
 18. A process of making a water treatment compositionincluding the steps of: a) mixing a first amount of silver nitrate intoa first batch of water to form a silver nitrate mixture; b) mixing afirst amount of sodium chloride into the silver nitrate mixture to forma silver chloride mixture; c) mixing an adhesive securable to bothsilver chloride and to support particles into a second batch of water toform an adhesive mixture; d) combing the silver chloride mixture and theadhesive mixture to form an adhesive silver chloride mixture; e)applying the adhesive silver chloride mixture to support particles; andf) curing the adhesive silver chloride mixture insitu on the supportparticles to form support particles having a coating containing silverchloride.
 19. The process of making a water treatment compositionaccording to claim 18 wherein mixing an adhesive into a second batch ofwater includes mixing polyvinyl acetate adhesive into a second batch ofwater.
 20. The process of making a water treatment composition accordingto claim 18 wherein mixing an adhesive into a second batch of waterincludes mixing polyurethane adhesive into a second batch of water. nor